Why is this medication prescribed?Didanosine is used with other medications to treat human immunodeficiency virus (HIV) infection in patients with or without acquired immunodeficiency syndrome (AIDS). Didanosine is in a class of medications called nucleoside reverse transcriptase inhibitors (NRTIs). Didanosine works by slowing the spread of HIV in the body. Didanosine does not cure HIV infection and may not prevent you from developing HIV-related illnesses. Didanosine does not prevent you from spreading HIV to other people.

How should this medicine be used?Didanosine comes as extended-release (long-acting) capsules, tablets that can be chewed or mixed with water, a powder to be mixed with water, and a solution (liquid). All are taken by mouth. Didanosine is usually taken once or twice a day on an empty stomach, 30 minutes before or 2 hours after eating. To help you remember to take didanosine, take it around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take didanosine exactly as directed. Do not take more or less of it, or take it more often than prescribed by your doctor.

If you are using the extended-release capsules, swallow them whole; do not split, chew, crush, or open them.

If you are using the tablets, do not swallow them whole. Chew the tablets well or mix them in at least 1 ounce of water and stir well to dissolve the tablets before swallowing. You may add one ounce (2 tablespoonfuls) of clear apple juice to the mixture for flavor, if needed. Do not use any other kind of juice. Drink all of the liquid right away.

If you are using the powder, you must mix it with water immediately before you take it. Open the packet and pour the powder into a glass with four ounces (1/2 cup) of water. Stir the mixture for 2 or 3 minutes until the powder is completely dissolved. Drink all of the liquid right away. Do not mix the powder with fruit juice or any other liquid.

If you are using the solution, you should shake it well before each use to mix the medication evenly. Use a dose-measuring spoon or cup to measure the correct dose, not a regular household spoon.

Didanosine controls HIV infection but does not cure it. Continue to take didanosine even if you feel well. Do not stop taking didanosine without talking to your doctor. If you miss doses or stop taking didanosine, your condition may become more difficult to treat.

Other uses for this medicineDidanosine is also used with another medication to help prevent infection in health care workers or other people who were accidentally exposed to HIV. Talk to your doctor about the possible risks of using this drug for your condition.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What special precautions should I follow?Before taking didanosine,

tell your doctor and pharmacist if you are allergic to didanosine, aspartame (Nutrasweet), antacids, or any other medications.

tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, and nutritional supplements you are taking. Be sure to mention any of the medications listed in the IMPORTANT WARNING section and the following: antacids; cancer chemotherapy medications; ganciclovir (Cytovene); methadone (Dolophine, Methadose); tenofovir (Viread); or zalcitabine (HIVID). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.

you should know that some medications must be taken several hours before or after you take didanosine. If you are taking any of the following medications, ask your doctor exactly when you should take them: anticoagulants ('blood thinners') such as warfarin (Coumadin); antifungals such as itraconazole (Sporanx) and ketoconazole (Nizoral); delavirdine (Rescriptor), digoxin (Lanoxin, Lanoxicaps); indinavir (Crixivan); nelfinavir (Viracept); quinolone antibiotics such as cinoxacin (Cinobac), ciprofloxacin (Cipro), enoxacin (Penetrex), gatifloxacin (Tequin), levofloxacin (Levaquin), lomefloxacin (Maxaquin), moxifloxacin (Avelox), nalidixic acid (NegGram), norfloxacin (Noroxin), ofloxacin (Floxin), sparfloxacin (Zagam), and trovafloxacin and alatrofloxacin combination (Trovan); tetracycline antibiotics such as demeclocycline (Declomycin), doxycycline (Doryx, Vibramycin), minocycline (Dynacin, Minocin), and tetracycline (Sumycin); and zinc supplements.

tell your doctor if you are on a low-salt diet and if you have or have ever had eye disease or problems with your vision, muscle problems, gout, peripheral neuropathy (numbness, tingling, burning, or pain sensation in your hands or feet, or decreased ability to feel temperature or touch in your hands or feet), radiation therapy, phenylketonuria (PKU, a disease in which you must avoid certain foods), or heart or kidney disease.

tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking didanosine, call your doctor. You should not breastfeed if you are infected with HIV or are taking didanosine.

you should know that didanosine may cause side effects that must be treated right away before they become serious. Children who are taking didanosine may not be able to tell you about the side effects they are feeling. If you are giving didanosine to a child, ask the child's doctor how you can tell if the child is having these serious side effects.

you should know that your body fat may increase or move to different areas of your body such as your breasts and upper back.

What special dietary instructions should I follow?Unless your doctor tells you otherwise, continue your normal diet.

What should I do if I forget a dose?Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What side effects can this medication cause?Didanosine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

diarrhea

headache

muscle pain

Some side effects can be serious. The following symptoms are uncommon, but if you experience any of them, or those mentioned in the IMPORTANT WARNING section, call your doctor immediately:

hives

skin rash

itching

difficulty breathing or swallowing

numbness, tingling, burning, or pain in hands or feet

blurred vision

difficulty in seeing colors clearly

chills

Didanosine may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

What storage conditions are needed for this medicine?Keep didanosine capsules, tablets, and powder in the containers they came in, tightly closed, and out of reach of children. Store them at room temperature and away from excess heat and moisture (not in the bathroom). Use mixtures of tablets and apple juice within 1 hour, and mixtures of powder and water within 4 hours. Keep didanosine liquid in the refrigerator, closed tightly, and throw away any unused medication after 30 days. Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

In case of emergency/overdoseIn case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

Symptoms of overdose may include:

diarrhea

numbness, tingling, burning, or pain in hands or feet

upset stomach

vomiting

loss of appetite

stomach pain

swelling of the stomach

severe back pain

extreme tiredness

weakness

dizziness

light-headedness

fast heart beat

sudden development of a slow or irregular heartbeat

deep or rapid breathing

shortness of breath

dark yellow or brown urine

unusual bleeding or bruising

yellowing of the skin or eyes

feeling cold

fever

flu-like symptoms

What other information should I know?Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

If you spill a packet of didanosine powder or didanosine liquid, clean the area of the spill with a wet mop or damp sponge using soap and water. Clean the area slowly so you do not make dust in the air. Try to keep all of the spill in one area. Wash your hands and the clean-up materials well after use.